Oceanic by Greg Egan Page B

the same for Alison and Yuen. There’d been no more reports of disasters on the radio, but the stations were probably as isolated now as their listeners. Ham operators would still be calling each other, but journalists and newsrooms would not be in the loop. I didn’t want to think about the contingency plans that might have been in place, given ten years’ preparation and an informed population.
    By the time I reached Penrith there were so many abandoned cars that the remaining traffic was almost gridlocked. I decided not to even try to reach home. I didn’t know if Sam had literally scanned my brain in Shanghai and used that to target what he’d done to me then, and whether or not he could use the same neuroanatomical information against me now, wherever I was, but staying away from my usual haunts seemed like one more small advantage to cling to.
    I found a petrol station, and it was giving priority to customers with functioning cars over hoarders who’d appeared on foot with empty cans. Their EFTPOS wasn’t working, but I had enough cash for the petrol and some chocolate bars.
    As dusk fell the streetlights came on; the traffic lights had never stopped working. All four laptops were holding up, hurling their grenades into the far side. The closer the attack front came to simple arithmetic, the more resistance it would face from natural processes voting at the border for near-side results. Our enemy had their supercomputers; we had every every atom of the Earth, following its billion-year-old version of the truth.
    We had modeled this scenario. The sheer arithmetical inertia of all that matter would buy us time, but in the long run a coherent, sustained, computational attack could still force its way through.
    How would we die? Losing consciousness first, feeling no pain? Or was the brain more robust than that? Would all the cells of our bodies start committing apoptosis, once their biochemical errors mounted up beyond repair? Maybe it would be just like radiation sickness. We’d be burned by decaying arithmetic, just as if it was nuclear fire.
    My laptop beeped. I swerved off the road and parked on a stretch of concrete beside a dark shopfront. A new icon had appeared on the screen: the letter S.
    Sam said, “Bruno, this was not my decision.”
    “I believe you,” I said. “But if you’re just a messenger now, what’s your message?”
    “If you give us what we asked for, we’ll stop the attack.”
    “We’re hurting you, aren’t we?”
    “We know we’re hurting you ,” Sam replied. Point taken: we were guessing, firing blind. He didn’t have to ask about the damage we’d suffered.
    I steeled myself, and followed the script the cabal had agreed upon. “We’ll give you the algorithm, but only if you retreat back to the old border, and then seal it.”
    Sam was silent for four long heartbeats.
    “Seal it?”
    “I think you know what I mean.” In Shanghai, when we’d used Luminous to try to ensure that Industrial Algebra could not exploit the defect, we’d contemplated trying to seal the border rather than eliminating the defect altogether. The voting effect could only shift the border if it was crinkled in such a way that propositions on one side could be outnumbered by those on the other side. It was possible – given enough time and computing power – to smooth the border, to iron it flat. Once that was done, everywhere, the whole thing would become immovable. No force in the universe could shift it again.
    Sam said, “You want to leave us with no weapon against you, while you still have the power to harm us.”
    “We won’t have that power for long. Once you know exactly what we’re using, you’ll find a way to block it.”
    There was a long pause. Then, “Stop your attacks on us, and we’ll consider your proposal.”
    “We’ll stop our attacks when you pull the border back to the point where our lives are no longer at risk.”
    “How would you even know that we’ve done that?”